diff --git a/Gemfile b/Gemfile
index 079376d..7eaa48b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,8 +13,9 @@ gem 'rspec_junit_formatter', '~> 0.4'
 gem 'rspec-mocks'
 gem 'rubocop', '0.54.0'
 
-gem "base64", "~> 0.2.0"
-gem "bigdecimal", "~> 3.1"
-gem "mutex_m", "~> 0.3.0"
 
 gem "concurrent-ruby", "~> 1.0", "< 1.3.5"
+
+gem "base64", ">= 0.2.0"
+gem "bigdecimal", ">= 3.1"
+gem "mutex_m", ">= 0.3.0"
diff --git a/Gemfile.lock b/Gemfile.lock
index e5b1a34..0417666 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -71,11 +71,11 @@ PLATFORMS
 
 DEPENDENCIES
   appraisal
-  base64 (~> 0.2.0)
-  bigdecimal (~> 3.1)
+  base64 (>= 0.2.0)
+  bigdecimal (>= 3.1)
   concurrent-ruby (~> 1.0, < 1.3.5)
   monotonic_tick_count!
-  mutex_m (~> 0.3.0)
+  mutex_m (>= 0.3.0)
   pry
   rake
   rspec (~> 3.7)